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Newer COVID variants less likely to affect smell and taste – US study

Omicron and other more recent variants of the coronavirus are less likely to have loss of smell and taste as indicators of infection in patients.

According to a study published in the journal Otolaryngology — Head and Neck Surgery, those infected with the Omicron variant have less chance of losing their smell and taste than those who contracted the Delta and other earlier COVID variants.

The chances of the symptoms of smell and taste loss occurring for the Omicron variant were just 17%, compared with much higher rates of these symptoms during the early phase of the pandemic in 2020.

Rates of these symptoms were greater for the Delta and Alpha variants, at 44% and 50% respectively, said researchers from the US.

“We now know that each variant has a different risk factor for associated smell and taste loss and have reason to believe that newer variants are less likely to impact smell and taste,” said Dr Daniel Coelho, an ear, nose and throat specialist and lead author of the study, from the Virginia Commonwealth University School of Medicine.

“Loss of smell and taste is still a good indicator of COVID infection, but the reverse is no longer true,” he added.

The Independent reports that the researchers assessed a national database of more than 3.5m cases of patients from the US who tested positive for COVID since the onset of the pandemic. They identified six-week periods where cases were highest for each variant studied and then compared how many patients were diagnosed with smell and taste loss in these timeframes.

“Patients infected with more recent variants are at a significantly lower risk of developing associated chemosensory loss,” they wrote.

Scientists believe comparing the variants and their effects could offer a clue in figuring out what part of the molecular structure of the virus causes such olfactory declines.

In further research, scientists hope to study the recovery time from smell and taste loss from different variants and understand if vaccination status plays a role in the reduced rates of these symptoms. They are also attempting to develop an implant device – similar to a cochlear implant that restores hearing for those with hearing loss – to restore the sense of smell.

“Patients with smell loss also have a higher rate of dementia. Fewer people experiencing these symptoms means fewer people being affected by mood changes and cognitive problems,” he added.

Study details

Decreasing Incidence of Chemosensory Changes by COVID-19 Variant
Daniel H. Coelho, Evan Reiter, Evan French, Richard Constanzo

Published in Otolaryngology — Head and Neck Surgery on 3 May 2022

Abstract
Anecdotal clinical observation suggests that rates of chemosensory dysfunction associated with COVID-19 infection may be decreasing. To investigate, the National COVID Cohort Collaborative database was queried for all patients with and without smell and taste loss within 2 weeks of COVID-19 diagnosis. Six-week periods of peak variant prevalence were selected by using CoVariants.org for analysis. Of 3,678,214 patients with COVID-19 in the database, 616,318 met inclusion criteria during the time intervals of interest, with 3431 having an associated smell or taste disturbance diagnosis. With the initial/untyped variant set as the baseline, the odds ratios for alpha, delta, and omicron (December 27, 2021–February 7, 2022) were 0.50 (95% CI, 0.45-0.55; P < .0001), 0.44 (95% CI, 0.41-0.48; P < .0001), and 0.17 (95% CI, 0.15-0.18; P < .0001), respectively.
These data strongly support the clinical observation that patients infected with more recent variants are at a significantly lower risk of developing associated chemosensory loss.

 

The Independent article – Omicron symptoms: Newer Covid variants less likely to have effect on taste and smell (Open access)

 

Otolaryngology — Head and Neck Surgery article – Decreasing Incidence of Chemosensory Changes by COVID-19 Variant (Open access)

 

See more from MedicalBrief archives:

 

Long-term damaged sense of smell in 50% of 1st wave COVID cases – Karolinska study

 

Association between loss of smell in after SARS-CoV-2 infection and cognitive impairment

 

French wine tasters ask for vaccine priority to protect sense of smell and taste

 

 

 

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